The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 04, 2014
Filed:
Apr. 18, 2011
Andreas Doktar, Vaasa, FI;
Stefan Strandberg, Vörå, FI;
Andreas Doktar, Vaasa, FI;
Stefan Strandberg, Vörå, FI;
Vacon Oyj, Vaasa, FI;
Abstract
Method and apparatus for measuring an earth fault current in an output circuit of an inverter (INU) operating on the PWM principle and forming alternating-current voltage from direct-current voltage, the output currents (i, iand i) of which inverter are measured, and which inverter comprises at least two phase switches implemented with power semiconductor components (V-V, D-D), which switches, controlled by a control unit, connect their own output phases to a positive (+) pole and to a negative (−) pole of a direct-current voltage source such that the phase switches are repeatedly both in different positions and also in the same positions, wherein the results of current measurement during two opposite switch position combinations are recorded in memory, and the earth fault current is calculated by forming a difference of the measurement results of said combinations.